1. Field of the Invention
This invention relates to an angle-of-rotation sensor for detecting the angle of rotation of a shaft. This invention particularly relates to an angle-of-rotation sensor for detecting the angle of rotation of the crankshaft of an internal combustion engine of an automobile or other such vehicle.
2. Description of the Prior Art
Recently, electronic control technology for internal combustion engines has been making rapid progress. With respect to such electronic control, control timing is important and as such it is necessary to detect with precision piston crank angle positions for use as reference signals. Conventional types of angle-of-rotation sensors include, for example, the type disclosed in Japanese Laid-open Patent Publication No. 57(1982)-133311. In this conventional technology rotating member is formed by stacking three disk-shaped magnets one on top of the other. Each of the magnets has magnetic poles formed contiguously around the periphery thereof, forming three arrays of magnetized zones.
However, because in this conventional type the rotating member is formed by the stacking of disk-shaped magnets, the rotating member becomes heavy, requiring that the diameter of the shaft be increased, with the result that other parts such as the bearings have had to be made large, so that overall the sensor becomes large and heavy, requiring a large space to house it in and causing a degradation in durability.
It is thereupon conceived that to form a rotating member a lighter magnetic member could be employed in place of the disk-shaped magnets, with a shaft arranged coaxially therein and the space therebetween filled with resin. However, it is not necessarily easy to firmly fasten the magnetic member to the shaft so that no slippage would occur therebetween, thus there is the problem of error arising in the detection output.